Semiconductor Manufacturing Process Monitor

The DIGILEM Series provides high precision detection of film thickness and trench depth during the etching/coating process.
Interference occurs when monochromatic light hits the sample surface, resulting in different optical path lengths due to film thickness and height variations in the film.
The system calculates the etching and coating speed of the monitored area by using time monitoring of the interference intensity based on the cycle, leading to detection of the end-point from the prescribed film thickness and trench depth.
Based on this relatively simple theory, the system is extremely stable and can be used with complex multi-layer films.

LEM-CT-670-G50/G120

[CCD]Laser Interference Camera

Two types of lasers are available and compatible with a broad range of films including SiN, SiO₂, GaAs, InP, AlGaAs, and GaN.

Features
The system consists of a compact interference measurement section that includes the light source, light detector, and optical components, as well as the illumination and CCD imaging camera, allowing microscopic image monitoring of any required area of the wafer surface. The system is compatible with a range of films by using visible (670 nm).

Sensor head
• Camera with CCD imaging
A large objective lens to wafer distance attachment range of 200 mm to 800 mm. The use of lasers enables a spot diameter as small as 20 μm to 100 μm. A compact, self-contained amplifier design that allows simple monitoring of 0 V to 10 V outputs with only a camera if connected to devices such as a pen recorder.

• Traditional interference wave type
The horizontal axes represents time. An interference cycle is generated with respect to the etching depth as the etching process progresses. The amount of etching during one cycle is displayed as Dp = λ (laser wavelength 670 nm) / 2n (refractive index of etching film).

DIGILEM-CPM-Xe/Halogen

[CCD]External Light Source Interference Camera


Perfect for monitoring thin and highly transparent films such as GaN, AlGaN, SiO₂, and SiN.

Features
The newly developed (patent pending) ultraviolet sensor head allows the device to be used for monitoring thin and highly transparent films. Variation in refractive index with this laser wavelength is small, which means films that could not be measured because of a lack of reflection can now be measured using the interference method, by selecting an arbitrary wavelength from the internal spectrometer.

Plasma spectrographic analysis is also possible
The DIGILEM-CPM type has an internal spectrometer which means emission spectral analysis and measurement of end-points is now possible in addition to interference measurements. A high performance spectrometer and waveform processing software means the system is compatible with weak optical signals with a poor S/N ratio.

Sensor head
• UV light interference: TILT HEAD
A shorter distance between the objective lens and wafer means the diameter of the spot can be decreased, so a long neck design has been used. This has been installed near the high cycle antenna, while the body of the main lens does not contain any metal parts.




Laser device etching monitor screen


An example of a complete system using a pattern recognition device. (The photo is the combination with the DIGILEM-CPM-Xe).

Common Features

• Completely compatible line software
This is a system for achieving high yield rates with semiconductors. Statistical processing from batch database compilation, remote control I/O common with the DIGI Series, and a remote control board for serial control from SECSII are included as standard features.

•End-point detection algorithms with improved flexibility
With HORIBA JOBIN YVON´s own alarm expansion settings feature, a large number of compatible algorithms for special signal detection and detection of signals with poor S/N ratios are included and can always be expanded.

•Advanced reprocessing features
Data obtained once can be simulated a number of times to achieve the optimum parameter configuration. This data can also be sent directly to HORIBA JOBIN YVON for analysis and optimization.

Specifications

•LEM-CT-670-G50/G120 Specifications

Motor X-Y stage, pattern recognition device

Memory 256 MB, CPU 600 Mhz or greater,
RAM 64 MB or greater, HDD 30 GB or greater

A measurement view port of Ø20 or greater will be required in a vertical direction across the wafer.